The wind scorpion is a colloquial name for a group of arthropods under the order Solifugae in the class Arachnida. Also known as sun spiders or camel spiders, the order Solifugae includes over 1,000 individual species of arthropod spread over 153 genera. Contrary to their popular names, wind scorpions are neither true scorpions nor true spiders, but a distinct grouping of arthropods. The name Solifugae comes from a Latin phrase meaning “to flee the sun,” which references their tendency to stay out of direct sunlight.
Wind scorpions are known for their intimidating appearance, long spindly legs, quick movement, fierce hunting tactics, and unusually large chelicerae (mandibles). They live primarily in dry arid environments and can be actually quite difficult to catch a glimpse of. They are most common in the Middle East, but wind scorpions inhabit almost most desert/arid regions on every continent except for Antarctica and Australia.
Solifugae have been known to humans for a long time. The Greeks recognized them as their own taxa, distinct from spiders and scorpions, and made note of their unique hunting abilities. Because of their frightening appearance, many urban legends have sprouted around wind scorpions and the potential dangers they pose to humans. These urban legends greatly exaggerate the size, speed, and aggression of wind scorpions. In actuality, wind scorpions are usually not aggressive towards humans unless threatened, instead preferring to stay out of the spotlight and quietly go about their hunting. Although not venomous, their jaws are capable of penetrating human skin and some have reported instances of wind scorpion bites. Generally, these bites, while they may be painful, are not medically significant and will heal properly.
Anatomy/Appearance
Myths about wind scorpions claim that they frequently grow to the size of dinner plates or larger. The truth is hardly so extraordinary though, as the various species of Solifugae range from just a half inch to about 6 inches including leg span. Females tend to have larger bodies and males have longer legs. Similar to spiders, their bodies are composed out of two main segments; a fused prosoma which includes the head and thorax, and a larger abdomen. Unlike spiders, their abdomens are inflexible and lack any silk-producing glands.
Although they look like they have 10 legs, they only have 8; the two large front appendages are pedipalps which they use to probe the environment and detect chemicals. At the end of their pedipalps are adhesive patches that they can use to snatch prey out of the air. Each of their 8 “true” legs are divided into 7 segments. The first pair of legs anterior to the pedipalps often acts to support the action of the pedipalps. Under the most posterior pair of legs, wind scorpions have a set of sensory organs known as malleoli, which are thought to sense mechanical vibrations in the ground.
Situated on top of the head are a pair of large simple eyes. These eyes are sophisticated and have a complex internal structure that may represent the final evolutionary step between the simple eye and the development of the compound eye. Some species of wind scorpion have a second pair of lateral eyes that are generally not as well developed as the main pair of eyes. Wind scorpions use their keen eyesight to target and hunt smaller prey.
The most distinguishing physical feature of wind scorpions is their large chelicerae which in some species are larger than the entire prosoma. The two chelicerae are shaped similar to crab claws, each with two segments connected by a joint. Lining the inside of each chelicera is a row of sharp teeth, the exact number of which varies by species. These jaws are strong and are wind scorpion’s primary hunting weapons. They easily cut through hair, feathers, and chitin, and can even crush the bones of smaller animals like birds.
When threatened, wind scorpions will rub their chelicerae together to produce sound, similar to how a cricket rubs its legs together. This sound is meant as a warning to potential threats and sounds like small clicks that can speed up or slow down depending on how threatened they feel. The fearsome appearance of their chelicerae is one source of the many urban legends surrounding wind scorpions.
Though they do not have proper lungs, wind scorpions breathe through a robust system of tracheae that draws in air through small holes on the creature’s underside. The air in the holes is pushed into the tracheae where oxygen diffuses across a membrane into the wind scorpions body. The same mechanisms are responsible for the exhalation of carbon dioxide waste products back into the atmosphere.
Behavior/Lifecycle
Wind scorpions subsist primarily on a diet of insects and small ground-dwelling arthropods; animals such as beetles, termites, and worms. They are voracious eaters and exceedingly effective hunters; even known to take down vertebrates like snakes, lizards, rodents and small birds. Generally active at dusk and the night, wind scorpions will stalk their hunting grounds, waiting to pounce on unsuspecting prey. Their weapon of choice while hunting is their large chelicerae which they use to kill and rip prey to pieces. They secrete an enzyme that liquifies their prey’s remains which they then swallow and digest. Their natural predators include bats, toads, and various insectivores. Scorpions, in particular, are known to get into very aggressive fights with wind scorpions, which normally end with one or the other being chopped into pieces or stung to death.
Wind scorpions are extremely quick and have been recorded running at speed of up to 10 mph. While running, they will lift their first set of legs off the ground and use their posterior 3 pairs of legs for propulsion. Wind scorpions are able to run so quickly because their respiratory system is very efficient at retrieving oxygen from the air. Oxygen allows for high-energy biological reactions which produce enough energy to let wind spiders at such high speeds. In addition to being fast sprinters, wind spiders are in general very agile and dexterous as they have precise control over their leg movements. They use their quick movement to catch prey off guard, sneaking up and pouncing before the prey has any time to react. Incidentally, their name as “wind” scorpions stems from their ability to run “as fast as the wind.”
Wind scorpions are univoltine organisms, meaning that they reproduce on brood every year. Wind scorpion mating is still not very well understood, but there is a general understanding of the process. In many species, the male will literally grab the female across their midsection with his chelicerae and stroke her with his pedipalps until she is in a receptive state. Then, the male will turn over the female, exposing her abdomen and genital openings. The male will deposit his sperm into the genitals with the chelicerae, and detach. In some species, the female does not have a genital opening, so the male will directly deposit his sperm into the ova by poking a hole in the abdomen. Wind scorpions have also been observed to engage in sexual cannibalism, where one of the mating pairs will consume the other after copulation. It is estimated that sexual cannibalism occurs in about 40% of wind scorpion mating encounters.
After copulation, the female will dig a burrow and lay her eggs. On average, wind scorpion females lay a single brood of 50-200 eggs. In a handful of species, the female will stick around to guard her eggs against threats, while others just leave the eggs and ensuing larvae to fend for themselves. Wind scorpions go through a number of developmental phases during their life from larva to nymph to adult. Although not certain, it is believed that most species of wind scorpion have an average lifespan of about one year, give or take a few months.
Wind Scorpions & Humans
There are several myths surrounding wind scorpions that greatly exaggerate their size, strength, speed, and aggression. It is often said that wind scorpions will endlessly chase after humans who run away. This is true to some extent, as wind scorpions do tend to follow humans when they move. However, this behavior is merely because they wish to rest in the cool shade of our shadows, not so they can attack. People claim that wind scorpions hunger for mammalian flesh, and can easily tear open a camel’s stomach. Again, this is exaggerated: the only mammals that wind scorpions have been seen to eat are rodents and they are nowhere near large or strong enough to kill a camel. Rumors also claim that they are extremely venomous, but as of 2018, there is no verified instance of a venomous species of wind scorpion.
Wind scorpions have recently gained popularity and recognition in the west during the Gulf war and the war in Iraq. Pictures sent home from allied soldiers showed the fearsome arthropods, often posed to make them look larger or more malicious than in real life. A recent case in England involved a family abandoning their house after discovering wind scorpion, which they blamed for the death of their dog.
Though they recently grabbed the attention of the west, wind scorpions have always been the stuff of legends in the Middle East. Roman naturalists thought that they were responsible for running off the populations in regions of Africa, and some Early Modern historians thought that records of biblical plagues involved wind scorpions. Soldiers stationed in the Middle East during WWI and WWII would regularly pit wind scorpions and real scorpions against each other for entertainment.
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If exposed to unkind elements, do wind scorpions have the ability to go into a torpor-looking dead and desiccated- and revive themselves when better conditions appear?
Had one do this last week. Would this be an evolutionary trait to deal with harsh desert conditions?